Then in 1869, a Russian scientist called Dmitri Mendeleev produced one of the first practical periodic tables ... in the middle of the table is called the Transition Metals.

The colors of rubies and emeralds are so striking that they define shades of red and green – ruby red and emerald green. But ...

Can France claim the first periodic ... first table contained just 28 elements, organised by their valency (how many other atoms they can combine with). These elements were almost entirely main group ...